Loading gear



Jan. 25, 1966 A. G. ALDEN 3,230,717

LOADING GEAR Filed May 8, 1964 M wwpwg W United States Patent 3,230,717LOADING GEAR Lars Anders Gustaf Aldn, Postlada 5150, Vaderhrunn,

Nykoping, Sweden Filed May s, 1964, Set. No. 366,096 2 Ciaims. ca.6054.5)

The invention relates to an improved loading gear having its loadsupporting portion pivoted in such a way to a horizontal axis at one endof at least one supporting arm pivoted to an upright frame member abouta horizontal axis, that the load supporting portion independently of thepivotment of the supporting arm relative to the frame member alwaysoccupies the same angular position relative to the ground by actuationof two coacting hydraulic operating cylinders one of which is pivotallymounted between the load supporting portion and the supporting arm whilethe other operating cylinder is pivotally mounted between the supportingarm and the frame member. The characteristic features of the inventionreside in that the operating cylinders are doubleacting and have theiroperating chambers communicating in pairs through direct conduitswhereby an entirely closed system is formed between the operatingcylinders. The invention thus provides the advantage that the loadsupporting portion is controlled without intervening pump, valves andtank.

The invention is diagrammatically illustrated by way of example in theaccompanying drawing which in side elevation shows the loading gear withthe supporting arm thereof in a horizontal position.

1 designates the upright frame member of a loading gear, and asupporting arm 2 is pivoted at 3 to the upper end of the frame member 1.The load supporting portion 4 is pivoted about a horizontal axis 5 atthe free end of the supporting arm 2 remote from the frame member 1. Theload supporting portion 4 consists of a loading plate 6 and a verticallyupwardly directed support 7 making a right angle with the plate 6.

A hydraulic operating cylinder 8 is pivotally mounted between thevertical support 7 of the load supporting portion 4 and the supportingarm 2 while another hydraulic operating cylinder 9 is pivotally mountedbetween the supporting arm 2 and the frame member 1. The pivot points 10and 11 of the operating cylinder 8 on the load supporting portion 4 andthe supporting arm 2 are so disposed as to form, with the pivot point 5of the load supporting portion 4 on the supporting arm 2, the corners ofa triangle which is similar or congruent with the triangle which thepivot points 12 and 13 of the operating cylinder 9 on the supporting arm2 and the frame 1 form with the pivot point 3 of the supporting arm 2 onthe frame 1.

The hydraulic operating cylinders 8 and 9 are doubleacting and theiroperating chambers communicate in pairs through direct conduits 1d and15. An entirely closed system is thus formed between the operatingcylinders 8 and 9. The operating cylinder 8 interposed between the loadsupporting portion 4 and the supporting arm 2 has its operating chamber,which adjoins the load supporting portion 4, in direct communicationthrough conduit 14 with the operating chamber of the operating cylinder9 interposed between the supporting arm 2 and the frame 1, said lastmentioned operating chamber adjoining the frame member 1. The other twooperating chambers of the operating cylinders 8 and 9 are directlyinterconnected through the conduit 15.

For example when the supporting arm 2 is swung upwards so that the anglebetween the supporting arm 2 and the frame member 1 is increased, thepiston in the operating cylinder 9 will reduce the volume of theoperating chamber adjoining the supporting arm 2 whereas the volume ofthe operating chamber situated on the other side of the pistonincreases. This will force the liquid in the first-mentioned operatingchamber through the conduit 15 into the operating chamber of theoperating cylinder 8, which chamber adjoins the supporting arm 2. As aresult, the piston in the operating cylinder 8 is urged toward the loadsupporting portion 4 which is thereby swung about the pivot axis 5. Thiswill reduce the volume of the operating chamber of the cylinder 8 thatadjoins the load supporting portion 4, and the liquid in this operatingchamber is urged through the conduit 14 to the operating chamber of thecylinder that adjoins the frame member 1.

Because of the dimensions and the location of the operating cylinders 8and 9 the load supporting portion 4 will always occupy the same angularposition relative to the ground irrespective of whether the supportingarm 2 is swung upwardly or downwardly relative to the pivot point 3 onthe frame member 1. The horizontal loading plate 6 will thus alwaysoccupy its horizontal position.

Different dimensions of the operating cylinders 8 and 9 can becompensated for by different pressure ratios in the conduits 14 and 15.However, the piston surfaces in two interconnected operating chambers inthe cylinders 8 and 9 shall always be equally large. In the embodimentillustrated this is realized in that the piston in the cylinder 9 isprovided with an extension 17 shaped like a piston rod and having twiceas large an area as the piston rod proper. In another embodiment thepistons in both operating cylinders 8 and 9 may be provided with pistonrod-shaped extensions 17 which in that case shall have the same area asthe piston rod proper.

A lifting cylinder 16 is adapted to impart to the supporting arm 2 thedesired pivotment thereof.

The above embodiment of the invention was described for purposes ofillustration rather than limitation. All possible variations andmodifications of the invention are understood as being included withinthe scope of the appended claims.

What I claim and desire to secure by Letters Patent is:

1. A loading gear comprising a frame, a supporting arm pivotally mountedat one end on said frame, a load supporting member pivoted to the otherend of said supporting arm, a first cylinder pivotally mounted on saidsupporting arm, a first piston movable in said first cylinder, a firstpiston rod for said piston pivotally connected at its free end to saidload supporting member, said first piston and first cylinder forming oneside of a first triangle whose corners are located at the pivoted pointsof said first piston rod, cylinder, and said load supporting member, asecond cylinder pivotally mounted on said frame, a second piston movablein said second cylinder, a second piston rod for said second pistonhaving its free end pivotally connected to said supporting arm, saidsecond cylinder and said second piston rod forming one side of a secondtriangle whose corners are located at the pivoted points of said secondpiston rod, said second cylinder and said supporting arm, said first andsecond pistons and cylinders being double acting and having operatingchambers communicating in pairs via direct conduits so that said loadsupporting member is pivoted when said supporting arm is pivoted, saidoperating chambers in said first and second cylinders above said firstand second pistons communicating through said direct conduits with thoseoperating chambers in said first and second cylinders below saidpistons, said communicating operating chambers having proportionaleffective areas and said first and second triangles having proportionalsides whereby said pistons will move uniformly in relation to saidcylinders When said supporting arm is pivoted so that said loadsupporting member during said pivoting movement will move parallel toitself.

2. A loading gear as claimed in claim 1 wherein one of said pistons isprovided with a piston rod-shaped extension below the piston forproviding proportional effective areas in the operating chambers.

References Cited by the Examiner UNITED STATES PATENTS Osgood.

Brock 6054.5 X Hemings 6097 Mindrum -21414O ROBERT R. BUNEVICH,Examiner.

1. A LOADING GEAR COMPRISING A FRAME, A SUPPORTING ARM PIVOTALLY MOUNTEDAT ONE END ON SAID FRAME, A LOAD SUPPORTING MEMBER PIVOTED TO THE OTHEREND OF SAID SUPPORTING ARM, A FIRST CYLINDER PIVOTALLY MOUNTED ON SAIDSUPPORTING ARM, A FIRST PISTON MOVABLE IN SAID FIRST CYLINDER, A FIRSTPISTON ROD FOR SAID PISTON PIVOTALLY CONNECTED AT ITS FREE END TO SAIDLOAD SUPPORTING MEMBER, SAID FIRST PISTON AND FIRST CYLINDER FORMING ONESIDE OF A FRIST TRIANGLE WHOSE CORNERS ARE LOCATED AT THE PIVOTATEDPOINTS OF SAID FIRST PISTON ROD, CYLINDER, AND SAID LOAD SUPPORTINGMEMBER, A SECOND CYLINDER PIVOTALLY MOUNTED ON SAID FRAME, A SECONDPISTON MOVABLE IN SAID SECOND CYLINDER, A SECOND PISTON ROD FOR SAIDSECOND PISTON HAVING ITS FREE END PIVOTALLY CONNECTED TO SAID SUPPORTINGARM, SAID SECOND CYLINDER AND SAID SECOND PISTON ROD FORMING ONE SIDE OFA SECOND TRIANGLE WHOSE CORNERS ARE LOCATED AT THE PIVOTED POINTS OFSAID SECON PISTON ROD, SAID SECOND CYLINDER AND SAID SUPPORTING ARM,SAID FIRST AND SECOND PISTONS AND CYLINDERS BEING DOUBLE ACTING ANDHAVING OPERATING CHAMBERS COMMUNICATING IN PAIRS VIA DIRECT CONDUITS SOTHAT SAID LOAD SUPPORTING MEMBER IS PIVOTED WHEN SAID SUPPORTING ARM ISPIVOTED, SAID OPERATING CHAMBERS IN SAID FIRST AND SECOND CYLINDERSABOVE SAID FIRST AND SECOND PISTONS COMMUNICATING THROUGH SAID DIRECTCONDUITS WITH THOSE OPERATING CHAMBERS IN SAID FIRST AND SECONDCYLINDERS BELOW SAID PISTONS, SAID COMMUNICATING OPERATING CHAMBERSHAVING PROPORTIONAL EFFECTIVE AREAS AND SAID FIRST AND SECOND TRIANGLESHAVING PROPORTIONAL SIDES WHEREBY SAID PISTONS WILL MOVE UNIFORMALY INRELATION TO SAID CYLINDERS WHEN SAID SUPPORTING ARM IS PIVOTED SO THATSAID LOAD SUPPORTING MEMBER DURING SAID PIVOTING MOVEMENT WILL MOVEPARALLEL TO ITSELF.